claude
c098933f25
Sync course wiki / sync-wiki (push) Successful in 4s
Co-authored-by: claude <claude@jpaul.io> Co-committed-by: claude <claude@jpaul.io>
96 lines
3.4 KiB
Bash
96 lines
3.4 KiB
Bash
#!/usr/bin/env bash
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#
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# deploy.sh: the deploy step of CD, simulated with a local container run.
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#
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# The five steps of any deploy, provider-neutral (see the module README):
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# 1. build/pull the specific image tag 4. health-check before trusting it
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# 2. inject runtime config + secrets 5. cut over if healthy, ROLL BACK if not
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# 3. start the new version
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#
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# The *target* here is your own machine instead of a server, but the logic is the real thing.
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#
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# Usage:
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# ./deploy.sh <tag> # e.g. ./deploy.sh $(git rev-parse --short HEAD)
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# BREAK=1 ./deploy.sh <tag># force the new version's health check to fail, to demo rollback
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#
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# Requires: docker (or `alias docker=podman`), curl.
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set -euo pipefail
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IMAGE="tasks-app"
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CONTAINER="tasks-app"
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PORT="8000"
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STATE_FILE=".deploy-state" # records the last good tag, for rollback
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TAG="${1:-$(git rev-parse --short HEAD)}"
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say() { printf '\n=== %s\n' "$*"; }
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# --- Step 1: build the artifact for this tag (in real CD this was already built+pushed by CI) -----
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say "Building ${IMAGE}:${TAG}"
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docker build -t "${IMAGE}:${TAG}" .
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# Remember what is currently running so we can roll back to it.
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PREVIOUS=""
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if [ -f "${STATE_FILE}" ]; then
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PREVIOUS="$(cat "${STATE_FILE}")"
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fi
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# --- Steps 2 + 3: start the new version with runtime config/secrets injected (Module 17) ----------
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# Note: APP_VERSION is config supplied at run time, NOT baked into the image. A real deploy would
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# also pass secrets here (e.g. --env-file, a mounted secret, or a secrets-manager lookup), never
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# committed, never in the image.
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start_version() {
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local tag="$1"
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docker rm -f "${CONTAINER}" >/dev/null 2>&1 || true
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docker run -d --name "${CONTAINER}" \
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-p "${PORT}:8000" \
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-e "APP_VERSION=${tag}" \
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${BREAK:+-e "BREAK=${BREAK}"} \
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"${IMAGE}:${tag}" >/dev/null
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}
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say "Starting ${IMAGE}:${TAG}"
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start_version "${TAG}"
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# --- Step 4: health-check the new version before trusting it --------------------------------------
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healthy() {
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for _ in $(seq 1 10); do
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if curl -fs "http://localhost:${PORT}/health" >/dev/null 2>&1; then
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return 0
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fi
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sleep 1
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done
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return 1
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}
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say "Health-checking http://localhost:${PORT}/health"
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if healthy; then
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# --- Step 5a: cut over. Record this as the new known-good for the next deploy's rollback target.
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echo "${TAG}" > "${STATE_FILE}"
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say "DEPLOY OK: ${IMAGE}:${TAG} is live and healthy"
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curl -s "http://localhost:${PORT}/health"; echo
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exit 0
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fi
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# --- Step 5b: ROLLBACK. The new version failed its health check. ----------------------------------
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say "HEALTH CHECK FAILED for ${IMAGE}:${TAG}, rolling back"
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docker rm -f "${CONTAINER}" >/dev/null 2>&1 || true
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if [ -z "${PREVIOUS}" ]; then
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echo "No previous known-good version to roll back to. Service is DOWN." >&2
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echo "(Deploy a healthy version first, then re-run the BREAK=1 deploy to see rollback work.)" >&2
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exit 1
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fi
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# Rollback is trivial because we deploy immutable tags: just run the old one again. No rebuild.
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say "Restoring previous good version ${IMAGE}:${PREVIOUS}"
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BREAK="" start_version "${PREVIOUS}" # clear BREAK so the good version comes up clean
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if healthy; then
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say "ROLLED BACK: ${IMAGE}:${PREVIOUS} is live and healthy. The bad deploy reverted itself."
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curl -s "http://localhost:${PORT}/health"; echo
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exit 1 # exit non-zero: the deploy you asked for did NOT ship, even though service recovered
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else
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echo "Rollback FAILED: service is DOWN. Investigate ${IMAGE}:${PREVIOUS}." >&2
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exit 2
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fi
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