Prometheus 2.0 migration guide

    In line with our stability promise, the Prometheus 2.0 release contains a number of backwards incompatible changes. This document offers guidance on migrating from Prometheus 1.8 to Prometheus 2.0 and newer versions.

    The format of Prometheus command line flags has changed. Instead of a single dash, all flags now use a double dash. Common flags (, --web.listen-address and --web.external-url) remain but almost all storage-related flags have been removed.

    Some notable flags which have been removed:

    • -alertmanager.url In Prometheus 2.0, the command line flags for configuring a static Alertmanager URL have been removed. Alertmanager must now be discovered via service discovery, see .

    • -log.format In Prometheus 2.0 logs can only be streamed to standard error.

    • -query.staleness-delta has been renamed to --query.lookback-delta; Prometheus 2.0 introduces a new mechanism for handling staleness, see staleness.

    • -storage.local.* Prometheus 2.0 introduces a new storage engine; as such all flags relating to the old engine have been removed. For information on the new engine, see .

    Alertmanager service discovery

    Alertmanager service discovery was introduced in Prometheus 1.4, allowing Prometheus to dynamically discover Alertmanager replicas using the same mechanism as scrape targets. In Prometheus 2.0, the command line flags for static Alertmanager config have been removed, so the following command line flag:

    Would be replaced with the following in the prometheus.yml config file:

    1. alerting:
    2.   alertmanagers:
    3.   - static_configs:
    4.     - targets:

    You can also use all the usual Prometheus service discovery integrations and relabeling in your Alertmanager configuration. This snippet instructs Prometheus to search for Kubernetes pods, in the default namespace, with the label name: alertmanager and with a non-empty port.

    1. alerting:
    2.   alertmanagers:
    3.   - kubernetes_sd_configs:
    4.       - role: pod
    6.       ca_file: /var/run/secrets/kubernetes.io/serviceaccount/ca.crt
    7.     bearer_token_file: /var/run/secrets/kubernetes.io/serviceaccount/token
    8.     relabel_configs:
    9.     - source_labels: [__meta_kubernetes_pod_label_name]
    10.       regex: alertmanager
    11.       action: keep
    12.     - source_labels: [__meta_kubernetes_namespace]
    13.       regex: default
    14.       action: keep
    15.     - source_labels: [__meta_kubernetes_pod_container_port_number]
    16.       regex:
    17.       action: drop

    The format for configuring alerting and recording rules has been changed to YAML. An example of a recording rule and alert in the old format:

    Would look like this:

    1. - name: example.rules
    2.   rules:
    3.   - record: job:request_duration_seconds:histogram_quantile99
    4.     expr: histogram_quantile(0.99, sum by (le, job) (rate(request_duration_seconds_bucket[1m])))
    5.   - alert: FrontendRequestLatency
    6.     expr: job:request_duration_seconds:histogram_quantile99{job="frontend"} > 0.1
    7.     for: 5m
    9.       summary: High frontend request latency

    To help with the change, the promtool tool has a mode to automate the rules conversion. Given a .rules file, it will output a .rules.yml file in the new format. For example:

    1. $ promtool update rules example.rules

    You will need to use promtool from as later versions no longer contain the above subcommand.

    Storage

    Your Prometheus 1.8 instance should be started with the following flags and an config file containing only the external_labels setting (if any):

    Prometheus 2.0 can then be started (on the same machine) with the following flags:

    1. $ ./prometheus-2.0.0.linux-amd64/prometheus --config.file prometheus.yml

    Where prometheus.yml contains in addition to your full existing configuration, the stanza:

    1. remote_read:
    2.   - url: "http://localhost:9094/api/v1/read"

    The following features have been removed from PromQL:

    • drop_common_labels function - the without aggregation modifier should be used instead.
    • keep_common aggregation modifier - the by modifier should be used instead.
    • count_scalar function - use cases are better handled by absent() or correct propagation of labels in operations.

    See for more details.

    Miscellaneous

    The Prometheus Docker image is now built to . If you want the Prometheus UI/API to listen on a low port number (say, port 80), you’ll need to override it. For Kubernetes, you would use the following YAML:

    See Configure a Security Context for a Pod or Container for more details.

    1. docker run -p 9090:9090 prom/prometheus:latest

    Prometheus lifecycle

    If you use the Prometheus /-/reload HTTP endpoint to automatically reload your Prometheus config when it changes, these endpoints are disabled by default for security reasons in Prometheus 2.0. To enable them, set the --web.enable-lifecycle flag.