Script for publishing buildbox build wait times as an AWS cloudwatch metric

buildbox_cloudwatch.sh

#!/bin/bash
#
# Publishes CloudWatch metrics about Buildbox queue length

set -e

API='https://api.buildbox.io'
BUILDS_ROUTE='v1/accounts/ACCOUNT_NAME/projects/PROJECT_NAME/builds'

# Determines whether a binary exists on the current $PATH
#
# Exits 0 if the binary was found in $PATH, or 1 if not found.
function in_path {
    local binary="$1"
    which "$binary" > /dev/null
}

# Echoes a JSON object representing the current build to stdout
function current_build {
    local url="$API/$BUILDS_ROUTE/$BUILDBOX_BUILD_NUMBER?api_key=$BUILDBOX_API_KEY"

    curl --fail "$url"
}

# Converts a Buildbox-style date to a Unix timestamp
function date_to_timestamp {
    local date="$1"

    if date --version 2> /dev/null | grep GNU > /dev/null; then
        # GNU date
        date --date="$date" '+%s'
    else
        # POSIX date
        date -ujf '%F %T UTC' "$date" '+%s'
    fi
}

# Echoes the number of seconds this build was scheduled for to stdout
function current_build_wait_time {
    local output='/tmp/curl-output'
    local scheduled_at
    local started_at

    # Save current build to avoid two requests
    current_build > "$output"

    # Pull out the scheduled_at and started_at fields
    scheduled_at="$(< "$output" jq -r '. | .scheduled_at')"
    started_at="$(< "$output" jq -r '. | .started_at')"

    # Echo the difference
    expr $(date_to_timestamp "$started_at") - $(date_to_timestamp "$scheduled_at")
}



echo "--- Determining this build's wait time"

wait_time=$(current_build_wait_time)
echo "This build had a wait time of $wait_time seconds."



echo '--- Publishing data point to CloudWatch'

aws cloudwatch put-metric-data \
    --metric-name ContestsBuildWaitTime \
    --namespace buildbox \
    --value "$wait_time" \
    --timestamp "$(date -u +'%FT%T.000Z')"

Could be improved by deriving the timestamp from the Buildkite job, rather than the "current time" at the point where it's submitted.