zzstoatzz.io
prefect server in zig
align defaults with python prefect server
- default host: 127.0.0.1 (was 0.0.0.0)
- default log level: WARNING (was INFO)
- default limits: 200 for work_pools/queues/workers (was 10)
- postgres pool_size: 5 (was 10)
- move config audit to docs/scratch/ (working notes, not permanent docs)
dev mode still uses DEBUG logging via justfile.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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docs/configuration-audit.md
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docs/configuration-audit.md
···
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# configuration audit
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comparison of magic values in zig implementation vs python prefect server settings.
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## http server
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| setting | zig value | python default | python env var | notes |
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|---------|-----------|----------------|----------------|-------|
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| port | 4200 | 4200 | `PREFECT_SERVER_API_PORT` | ✅ matches |
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| host | 0.0.0.0 | 127.0.0.1 | `PREFECT_SERVER_API_HOST` | zig binds all interfaces by default |
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| workers | 1 | 1 | `--workers` CLI flag | ✅ matches |
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| threads | 4 | n/a | - | zap/facil.io specific; python uses async |
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| max_clients | 1000 | n/a | - | zap/facil.io specific; uvicorn unlimited |
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| max_body_size | 16MB | n/a | - | uvicorn default is unlimited |
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| keepalive_timeout | n/a | 5s | `PREFECT_SERVER_API_KEEPALIVE_TIMEOUT` | not implemented in zig |
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### recommendations
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- **host**: consider defaulting to `127.0.0.1` for security parity, allow override via `PREFECT_SERVER_API_HOST`
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- **threads/workers**: zap's model is different (threads per worker). current 4 threads × 1 worker is reasonable for single-process mode
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- **max_body_size**: 16MB is reasonable; python has no limit which could be a DoS vector
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- **keepalive_timeout**: consider adding support
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## api behavior
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| setting | zig value | python default | python env var | notes |
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|---------|-----------|----------------|----------------|-------|
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| default_limit | varies | 200 | `PREFECT_SERVER_API_DEFAULT_LIMIT` | see breakdown below |
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### hardcoded limits by endpoint
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| endpoint | zig limit | python default | location |
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|----------|-----------|----------------|----------|
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| deployments/filter | 200 | 200 | deployments.zig:316 |
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| deployments/get_scheduled_flow_runs | 100 | 200 | deployments.zig:523 |
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| variables/filter | 200 | 200 | variables.zig:322 |
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| work_pools/filter | 10 | 200 | work_pools.zig:429 |
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| work_pool_queues/filter | 10 | 200 | work_pool_queues.zig:254 |
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| work_pool_workers/filter | 10 | 200 | work_pool_workers.zig:86 |
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### recommendations
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- make default_limit configurable via `PREFECT_SERVER_API_DEFAULT_LIMIT`
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- align work_pools/workers/queues limits to 200 for parity
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## database
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| setting | zig value | python default | python env var | notes |
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|---------|-----------|----------------|----------------|-------|
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| pool_size | 10 (hardcoded in backend.zig:275) | 5 | `PREFECT_SERVER_DATABASE_SQLALCHEMY_POOL_SIZE` | zig uses larger pool |
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| max_overflow | n/a | 10 | `PREFECT_SERVER_DATABASE_SQLALCHEMY_MAX_OVERFLOW` | not applicable to pg.zig |
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| pool_recycle | n/a | 3600s | - | not implemented |
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| statement_timeout | n/a | 10s | `PREFECT_SERVER_DATABASE_TIMEOUT` | not implemented |
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| connection_timeout | n/a | 5s | `PREFECT_SERVER_DATABASE_CONNECTION_TIMEOUT` | not implemented |
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### recommendations
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- make pool_size configurable via `PREFECT_DATABASE_POOL_SIZE` (default 10 is fine)
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- statement and connection timeouts would be good to add for production safety
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## events
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| setting | zig value | python default | python env var | notes |
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|---------|-----------|----------------|----------------|-------|
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| max_event_size | n/a | 1.5MB | `PREFECT_SERVER_EVENTS_MAXIMUM_SIZE_BYTES` | not validated in zig |
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| max_related_resources | n/a | 100 | `PREFECT_SERVER_EVENTS_MAXIMUM_RELATED_RESOURCES` | not validated |
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| max_labels_per_resource | n/a | 500 | `PREFECT_SERVER_EVENTS_MAXIMUM_LABELS_PER_RESOURCE` | not validated |
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| retention_period | n/a | 7 days | `PREFECT_SERVER_EVENTS_RETENTION_PERIOD` | not implemented |
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| websocket_backfill_page_size | 250 | 250 | `PREFECT_SERVER_EVENTS_WEBSOCKET_BACKFILL_PAGE_SIZE` | ✅ matches |
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| max_websocket_backfill | 15min | 15min | `PREFECT_SERVER_EVENTS_MAXIMUM_WEBSOCKET_BACKFILL` | ✅ matches |
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### recommendations
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- event validation (size, related resources, labels) would improve API parity
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- retention cleanup service would be good for production
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## logging
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| setting | zig value | python default | python env var | notes |
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|---------|-----------|----------------|----------------|-------|
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| level | INFO | WARNING | `PREFECT_SERVER_LOGGING_LEVEL` | zig more verbose by default |
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### recommendations
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- consider defaulting to WARNING to match python
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## deployments
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| setting | zig value | python default | python env var | notes |
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|---------|-----------|----------------|----------------|-------|
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| schedule_max_runs | n/a | 50 | `PREFECT_SERVER_DEPLOYMENT_SCHEDULE_MAX_SCHEDULED_RUNS` | scheduler not implemented yet |
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## action items
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### high priority (behavioral parity)
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1. default host to 127.0.0.1
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2. default logging level to WARNING
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### medium priority (production safety)
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3. add database statement timeout
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4. add event size validation
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5. add keepalive timeout support
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### low priority (completeness)
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6. event retention cleanup
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7. deployment scheduler service
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docs/scratch/configuration-audit.md
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docs/scratch/configuration-audit.md
···
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# configuration audit
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comparison of magic values in zig implementation vs python prefect server settings.
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**status**: most high-priority items addressed, remaining items are medium/low priority
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## http server
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| setting | zig value | python default | python env var | notes |
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|---------|-----------|----------------|----------------|-------|
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| port | 4200 | 4200 | `PREFECT_SERVER_API_PORT` | ✅ matches |
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| host | 127.0.0.1 | 127.0.0.1 | `PREFECT_SERVER_API_HOST` | ✅ matches |
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| workers | 1 | 1 | `--workers` CLI flag | ✅ matches |
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| threads | 4 | n/a | - | zap/facil.io specific; python uses async |
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| max_clients | 1000 | n/a | - | zap/facil.io specific; uvicorn unlimited |
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| max_body_size | 16MB | n/a | - | uvicorn default is unlimited |
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| keepalive_timeout | n/a | 5s | `PREFECT_SERVER_API_KEEPALIVE_TIMEOUT` | not implemented in zig |
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### notes
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- **threads/workers**: zap's model is different (threads per worker). 4 threads × 1 worker is reasonable for single-process mode
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- **max_body_size**: 16MB is reasonable; python has no limit which could be a DoS vector
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## api behavior
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| setting | zig value | python default | python env var | notes |
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|---------|-----------|----------------|----------------|-------|
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| default_limit | 200 | 200 | `PREFECT_SERVER_API_DEFAULT_LIMIT` | ✅ matches (all endpoints) |
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## database
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| setting | zig value | python default | python env var | notes |
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|---------|-----------|----------------|----------------|-------|
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| pool_size | 5 | 5 | `PREFECT_SERVER_DATABASE_SQLALCHEMY_POOL_SIZE` | ✅ matches |
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| max_overflow | n/a | 10 | `PREFECT_SERVER_DATABASE_SQLALCHEMY_MAX_OVERFLOW` | not applicable to pg.zig |
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| pool_recycle | n/a | 3600s | - | not implemented |
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| statement_timeout | n/a | 10s | `PREFECT_SERVER_DATABASE_TIMEOUT` | not implemented |
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| connection_timeout | n/a | 5s | `PREFECT_SERVER_DATABASE_CONNECTION_TIMEOUT` | not implemented |
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## events
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| setting | zig value | python default | python env var | notes |
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|---------|-----------|----------------|----------------|-------|
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| max_event_size | n/a | 1.5MB | `PREFECT_SERVER_EVENTS_MAXIMUM_SIZE_BYTES` | not validated in zig |
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| max_related_resources | n/a | 100 | `PREFECT_SERVER_EVENTS_MAXIMUM_RELATED_RESOURCES` | not validated |
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| max_labels_per_resource | n/a | 500 | `PREFECT_SERVER_EVENTS_MAXIMUM_LABELS_PER_RESOURCE` | not validated |
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| retention_period | n/a | 7 days | `PREFECT_SERVER_EVENTS_RETENTION_PERIOD` | not implemented |
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| websocket_backfill_page_size | 250 | 250 | `PREFECT_SERVER_EVENTS_WEBSOCKET_BACKFILL_PAGE_SIZE` | ✅ matches |
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| max_websocket_backfill | 15min | 15min | `PREFECT_SERVER_EVENTS_MAXIMUM_WEBSOCKET_BACKFILL` | ✅ matches |
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## logging
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| setting | zig value | python default | python env var | notes |
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|---------|-----------|----------------|----------------|-------|
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| level | WARNING | WARNING | `PREFECT_SERVER_LOGGING_LEVEL` | ✅ matches |
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## deployments
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| setting | zig value | python default | python env var | notes |
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|---------|-----------|----------------|----------------|-------|
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| schedule_max_runs | n/a | 50 | `PREFECT_SERVER_DEPLOYMENT_SCHEDULE_MAX_SCHEDULED_RUNS` | scheduler not implemented yet |
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## remaining work
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### medium priority (production safety)
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- add database statement timeout
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- add event size validation
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- add keepalive timeout support
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### low priority (completeness)
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- event retention cleanup service
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- deployment scheduler service
+1
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src/api/work_pool_queues.zig
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src/api/work_pool_queues.zig
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src/api/work_pool_workers.zig
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src/api/work_pool_workers.zig
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src/api/work_pools.zig
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src/api/work_pools.zig
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src/db/CLAUDE.md
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src/db/CLAUDE.md
···
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- `Backend` union type for sqlite/postgres
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- unified `Row` interface for column access
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- automatic placeholder rewriting (`?` → `$1, $2` for postgres)
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- connection pool for postgres (size=10), mutex for sqlite
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- connection pool for postgres (size=5), mutex for sqlite
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## env vars
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src/db/backend.zig
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src/db/backend.zig
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src/logging.zig
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src/logging.zig
···
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if (std.ascii.eqlIgnoreCase(s, "WARNING") or std.ascii.eqlIgnoreCase(s, "WARN")) return .warning;
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if (std.ascii.eqlIgnoreCase(s, "ERROR")) return .err;
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if (std.ascii.eqlIgnoreCase(s, "CRITICAL")) return .critical;
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return .info;
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return .warning;
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}
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pub fn name(self: Level) []const u8 {
···
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}
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};
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var server_level: Level = .info;
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var server_level: Level = .warning;
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pub fn init() void {
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if (posix.getenv("PREFECT_SERVER_LOGGING_LEVEL")) |level_str| {
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src/main.zig
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src/main.zig
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break :blk std.fmt.parseInt(u16, port_str, 10) catch 4200;
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};
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const host = posix.getenv("PREFECT_SERVER_API_HOST") orelse "127.0.0.1";
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log.info("database", "initializing...", .{});
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try db.init();
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defer db.close();
···
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var listener = zap.HttpListener.init(.{
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.port = port,
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.interface = host.ptr,
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.on_request = onRequest,
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.on_upgrade = events.onUpgrade,
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.log = true,
···
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});
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try listener.listen();
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log.info("server", "listening on http://0.0.0.0:{d}", .{port});
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log.info("server", "listening on http://{s}:{d}", .{ host, port });
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zap.start(.{
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.threads = 4,