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111 lines
3.7 KiB
Markdown
111 lines
3.7 KiB
Markdown
---
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title: Renew a Certificate
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date: 2019-03-03T16:39:46+01:00
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draft: false
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weight: 3
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---
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This guide describes how to renew existing certificates.
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<!--more-->
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Certificates issues by Let's Encrypt are valid for a period of 90 days.
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To avoid certificate errors, you need to ensure that you renew your certificate *before* it expires.
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In order to renew a certificate, follow the general instructions laid out under [Obtain a Certificate]({{< ref "usage/cli/Obtain-a-Certificate" >}}), and replace `lego ... run` with `lego ... renew`.
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Note that the `renew` sub-command supports a slightly different set of some command line flags.
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## Using the built-in web server
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By default, and following best practices, a certificate is only renewed if its expiry date is less than 30 days in the future.
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```bash
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lego --email="you@example.com" --domains="example.com" --http renew
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```
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If the certificate needs to renewed earlier, you can specify the number of remaining days:
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```bash
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lego --email="you@example.com" --domains="example.com" --http renew --days 45
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```
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## Using a DNS provider
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If you can't or don't want to start a web server, you need to use a DNS provider.
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lego comes with [support for many]({{< ref "dns#dns-providers" >}}) providers,
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and you need to pick the one where your domain's DNS settings are set up.
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Typically, this is the registrar where you bought the domain, but in some cases this can be another third-party provider.
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For this example, let's assume you have set up CloudFlare for your domain.
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Execute this command:
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```bash
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CLOUDFLARE_EMAIL="you@example.com" \
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CLOUDFLARE_API_KEY="yourprivatecloudflareapikey" \
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lego --email "you@example.com" --dns cloudflare --domains "example.org" renew
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```
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## Running a script afterward
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You can easily hook into the certificate-obtaining process by providing the path to a script.
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The hook is executed only when the certificates are effectively renewed.
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```bash
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lego --email="you@example.com" --domains="example.com" --http renew --renew-hook="./myscript.sh"
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```
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Some information is provided through environment variables:
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- `LEGO_ACCOUNT_EMAIL`: the email of the account.
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- `LEGO_CERT_DOMAIN`: the main domain of the certificate.
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- `LEGO_CERT_PATH`: the path of the certificate.
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- `LEGO_CERT_KEY_PATH`: the path of the certificate key.
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See [Obtain a Certificate → Use case]({{< ref "usage/cli/Obtain-a-Certificate#use-case" >}}) for an example script.
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## Automatic renewal
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It is tempting to create a cron job (or systemd timer) to automatically renew all you certificates.
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When doing so, please note that some cron defaults will cause measurable load on the ACME provider's infrastructure.
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Notably `@daily` jobs run at midnight.
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To both counteract load spikes (caused by all lego users) and reduce subsequent renewal failures, we were asked to implement a small random delay for non-interactive renewals.[^loadspikes]
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Since v4.8.0, lego will pause for up to 8 minutes to help spread the load.
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You can help further, by adjusting your crontab entry, like so:
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```ruby
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# avoid:
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#@daily /usr/bin/lego ... renew
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#@midnight /usr/bin/lego ... renew
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#0 0 * * * /usr/bin/lego ... renew
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# instead, use a randomly chosen time:
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35 3 * * * /usr/bin/lego ... renew
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```
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If you use systemd timers, consider doing something similar, and/or introduce a `RandomizedDelaySec`:
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```ini
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[Unit]
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Description=Renew certificates
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[Timer]
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Persistent=true
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# avoid:
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#OnCalendar=*-*-* 00:00:00
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#OnCalendar=daily
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# instead, use a randomly chosen time:
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OnCalendar=*-*-* 3:35
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# add extra delay, here up to 1 hour:
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RandomizedDelaySec=1h
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[Install]
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WantedBy=timers.target
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```
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[^loadspikes]: See [GitHub issue #1656](https://github.com/go-acme/lego/issues/1656) for an excellent problem description.
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