sneal · August 13, 2024 21:02 · Aug 13, 2024
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+TAS 4.0.20+ has ability to limit the log rate (bytes/sec) of applications to avoid having a single application overwhelm the logging system in Cloud Foundry.
+
+The general settings or ways to configure logging limits are:
+- "Default log rate limit per app" in the TAS tile under App Developer Controls
+- CF org/space quotas
+- log-rate-limit-per-second app setting
+
+## Default log rate limit per app
+The global default setting is just that, a default. It's the same as setting the per-app `log-rate-limit-per-second` on
+every single app in the foundation. This is not a way to keep devs from overriding this value. Devs can override
+the global default value with a higher or lower `log-rate-limit-per-second` value.
+
+> __NOTE__ - If you've implemented quotas with log rate limits, it's important this setting isn't too large compared to the quota or you may unintentionally cause `cf push` to fail for entire orgs/spaces.
+
+## CF org/space quotas
+
+The log rate quota value behaves just like any other quota value, setting a cap on shared resources within an org/space.
+
+Setting a log rate limit in a quota is not the same as setting a `log-rate-limit-per-second` value. The quota value
+is the MAX value the `log-rate-limit-per-second` can be set to and since the global default is essentially the same
+as setting this per app, the quota applies to the global setting as well.
+
+What does that mean? If you set an org log quota of 2048 bytes/sec but you set the global default to 4096 bytes/sec,
+you'll get a cf push error "organization's log rate limit exceeded: staging requires 4096 bytes per second".
+
+The other thing to note about the quota log rate limit value is that it takes into account all apps within the assigned
+org/space when calculating whether you have enough headroom. If you set an org log quota of 2048 bytes/sec and have two
+apps with a `log-rate-limit-per-second` of 1024 bytes/sec - everything is fine (1024 + 1024 = 2048), at least until you try to push a 3rd
+app (1024 + 1024 + 1024 = 3072).
+
+Just remember the quota is not implementing the log rate limit, it's capping the log rate limit settings within the org/space.
+
+## log-rate-limit-per-second App Setting
+This is the value that can be set per app in the application manifest as `log-rate-limit-per-second` or via the cf scale
+command after the fact. This value by default is unlimited (unset) unless a default global log rate limit has been set. A dev
+can override this value to any setting below or even above the default value - the global value is just a default. The
+important thing to keep in mind is that cf quotas can limit the max this value can be set to, and needs to fit within
+the org/space quota alongside all other apps within the org/space.
+
+
diff --git a/test-output.txt b/test-output.txt
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+
+Global default limit: 2048b
+Org quota limit: not set
+App limit: not set
+Result: App uses default global limit, "app instance exceeded log rate limit (2048 bytes/sec)"
+
+
+Global default limit: 2048b
+Org quota limit: 3000b
+App limit: not set
+Result: App uses default global limit, "app instance exceeded log rate limit (2048 bytes/sec)"
+
+
+Global default limit: 2700b
+Org quota limit: 2048b
+App limit: not set
+Result: Can't push the app, "organization's log rate limit exceeded: staging requires 2700 bytes per second"
+
+
+Global default limit: 2700b
+Org quota limit: 2701b
+App limit: not set
+Result: App uses default global limit, "app instance exceeded log rate limit (2700 bytes/sec)"
+
+
+Global default limit: 2700b
+Org quota limit: 2701b
+App limit: 2800b
+Result: Can't push the app, "organization's log rate limit exceeded: staging requires 2800 bytes per second"
+
+
+Global default limit: 2700b
+Org quota limit: 2800b
+App limit: 2750b
+Result: App uses the app limit, "app instance exceeded log rate limit (2750 bytes/sec)"
+
+
+Global default limit: 2700b
+Org quota limit: unlimited
+App limit: 2750b
+Result: App uses the app limit, "app instance exceeded log rate limit (2750 bytes/sec)"
+
+
+Global default limit: 2700b
+Org quota limit: unlimited
+App limit: 2048b
+Result: App uses the app limit, "app instance exceeded log rate limit (2048 bytes/sec)"
+
+
+Global default limit: 2700b
+Org quota limit: unlimited
+App limit: 2800b
+Result: App uses the app limit, "app instance exceeded log rate limit (2800 bytes/sec)"
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