Supercronic job suddenly not working

Questions / Help
1

Supercronic job setup that previously was working fine suddenly stopped working. This is my setup.

Dockerfile:

# syntax = docker/dockerfile:1

# Adjust BUN_VERSION as desired
ARG BUN_VERSION=1.1.40-slim
FROM oven/bun:${BUN_VERSION} as base

LABEL fly_launch_runtime="Bun"

# Bun app lives here
WORKDIR /app

# Install curl
RUN apt-get update -qq && \
    apt-get install --no-install-recommends -y ca-certificates curl gnupg && \
    rm -rf /var/lib/apt/lists /var/cache/apt/archives

# Latest releases available at https://github.com/aptible/supercronic/releases
ENV SUPERCRONIC_URL=https://github.com/aptible/supercronic/releases/download/v0.2.29/supercronic-linux-amd64 \
SUPERCRONIC=supercronic-linux-amd64 \
SUPERCRONIC_SHA1SUM=cd48d45c4b10f3f0bfdd3a57d054cd05ac96812b

RUN curl -fsSLO "$SUPERCRONIC_URL" \
&& echo "${SUPERCRONIC_SHA1SUM}  ${SUPERCRONIC}" | sha1sum -c - \
&& chmod +x "$SUPERCRONIC" \
&& mv "$SUPERCRONIC" "/usr/local/bin/${SUPERCRONIC}" \
&& ln -s "/usr/local/bin/${SUPERCRONIC}" /usr/local/bin/supercronic

# Copy the crontab file
COPY crontab /app/crontab

# Install npm modules
COPY --link bun.lockb package.json ./
RUN bun install --production --frozen-lockfile

# Create a non-root user to run the app
RUN useradd chrome --create-home --shell /bin/bash && \
    chmod -R +r /app/node_modules
USER chrome:chrome

# Copy application code
COPY --link . .

# Start the server
# CMD [ "bun", "run", "start" ]

# Run the app and the cron process
CMD ["sh", "-c", "bun run start & supercronic /app/crontab"]

fly.toml:

app = 'workhours-scrapper'
primary_region = 'otp'
swap_size_mb = 2048

[build]

[env]
  FORMAT = 'letter'
  JAVASCRIPT = 'false'
  TIMEOUT = '15'

[http_service]
  internal_port = 3000
  force_https = false
  auto_stop_machines = false
  auto_start_machines = true
  min_machines_running = 0
  processes = ['app']

  [http_service.concurrency]
    type = 'requests'
    hard_limit = 5
    soft_limit = 3

[[vm]]
  cpu_kind = 'shared'
  cpus = 1
  memory_mb = 1024

[processes]
  app = "bun run start"
  cron = "supercronic /app/crontab"

Crontab file:

00 22 * * * curl http://my-app.flycast/api/scrape

Any ideas what could be the reason that cron job is not triggered anymore?

2

Shell into the app, grab the Supercronic logs please, and post them here.

How many machines do you have in this app?

3

When I run supercronic -debug crontab I get:

INFO[2025-03-10T13:32:14Z] read crontab: crontab
DEBU[2025-03-10T13:32:14Z] try parse (6 fields): '00 22 * * * curl'
DEBU[2025-03-10T13:32:14Z] failed to parse (6 fields): '00 22 * * * curl': failed: syntax error in year field: 'curl'
DEBU[2025-03-10T13:32:14Z] try parse (5 fields): '00 22 * * *'
DEBU[2025-03-10T13:32:14Z] job will run next at 2025-03-10 22:00:00 +0000 UTC  job.command="curl http://my-app.flycast/api/scrape" job.position=0 job.schedule="00 22 * * *"

I have two machines:

image
image633×229 12.3 KB

4

OK. This looks like the reason; you have a syntax error in your schedule spec:

5

Ah, coolio. It looks like you have one machine for the runner process, which is probably not a bad thing for a scheduler. If you run more than one instance of a scheduler it will usually run all of your tasks several times, which in turn can produce some weird race conditions.

6

Are you sure this could be the reason why the job is not running? My understanding was that it tries to parse the cron expression as 6 fields format, but it fails. Then it tries to parse it as 5 fields format, which is successful and then the next job is scheduled:

DEBU[2025-03-10T13:32:14Z] job will run next at 2025-03-10 22:00:00 +0000 UTC  job.command="curl http://my-app.flycast/api/scrape" job.position=0 job.schedule="00 22 * * *"

But this job never gets executed.

7

Ah, I think you might be right. I’d amend the format then so it erases that error. It looks like it just needs seconds adding at the start:

00 00 22 * * * curl http://my-app.flycast/api/scrape

Alternatively there’s some scheduler debug approaches in the Supercronic README.

8

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