Companion code for Zero-Downtime Database Migrations: Expand-Contract in Practice with Spring Boot: a full expand/migrate-writes/migrate-reads/contract sequence run as an actual rolling deploy across two live replicas, with a load generator sending continuous HTTP traffic through all four deploys (99.98% success, every residual error traced to a root cause rather than left unexplained). Findings include a real NOT NULL constraint trap in the expand migration, a backfill-window bug in the read switch, H2's AUTO_SERVER=TRUE single-point-of-failure behavior under a rolling restart, the drain-before-SIGTERM fix needed to close a health-check gap during graceful shutdown, and H2 silently discarding a concurrently committed INSERT during an ALTER TABLE ADD/DROP COLUMN rebuild - confirmed, by primary source, to be an H2-specific behavior rather than a property of the technique itself. Co-Authored-By: Claude Sonnet 5 <[email protected]> Claude-Session: https://claude.ai/code/session_019Fb7vW8vLyLKngBc4R3huA
11 lines
404 B
Bash
Executable File
11 lines
404 B
Bash
Executable File
#!/usr/bin/env bash
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# Runs the standalone migration.MigrationCli against the live database - no app
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# restart, no app deploy. Usage: migrate.sh <target|latest>
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set -euo pipefail
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DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
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source "$DIR/env.sh"
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TARGET="${1:-latest}"
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java -cp "$MODULE_DIR/target/classes:$(cat "$CP_FILE")" \
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com.ankurm.expandcontract.migration.MigrationCli --target="$TARGET"
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