Gilles has uploaded a new change for review. (
https://gerrit.wikimedia.org/r/372543 )
Change subject: Add Prometheus lua script for nginx-full
......................................................................
Add Prometheus lua script for nginx-full
Bug: T151554
Change-Id: Ief5b2f0719f3edcf53bc9646c4bfccd4b6f4db24
---
A files/prometheus.lua
M manifests/init.pp
2 files changed, 537 insertions(+), 0 deletions(-)
git pull ssh://gerrit.wikimedia.org:29418/operations/puppet/nginx
refs/changes/43/372543/1
diff --git a/files/prometheus.lua b/files/prometheus.lua
new file mode 100644
index 0000000..8af3ba1
--- /dev/null
+++ b/files/prometheus.lua
@@ -0,0 +1,529 @@
+-- vim: ts=2:sw=2:sts=2:expandtab
+--
+-- This module uses a single dictionary shared between Nginx workers to keep
+-- all metrics. Each counter is stored as a separate entry in that dictionary,
+-- which allows us to increment them using built-in `incr` method.
+--
+-- Prometheus requires that (a) all samples for a given metric are presented
+-- as one uninterrupted group, and (b) buckets of a histogram appear in
+-- increasing numerical order. We satisfy that by carefully constructing full
+-- metric names (i.e. metric name along with all labels) so that they meet
+-- those requirements while being sorted alphabetically. In particular:
+--
+-- * all labels for a given metric are presented in reproducible order (the
one
+-- used when labels were declared). "le" label for histogram metrics always
+-- goes last;
+-- * bucket boundaries (which are exposed as values of the "le" label) are
+-- presented as floating point numbers with leading and trailing zeroes.
+-- Number of of zeroes is determined for each bucketer automatically based
on
+-- bucket boundaries;
+-- * internally "+Inf" bucket is stored as "Inf" (to make it appear after
+-- all numeric buckets), and gets replaced by "+Inf" just before we
+-- expose the metrics.
+--
+-- For example, if you define your bucket boundaries as {0.00005, 10, 1000}
+-- then we will keep the following samples for a metric `m1` with label
+-- `site` set to `site1`:
+--
+-- m1_bucket{site="site1",le="0000.00005"}
+-- m1_bucket{site="site1",le="0010.00000"}
+-- m1_bucket{site="site1",le="1000.00000"}
+-- m1_bucket{site="site1",le="Inf"}
+-- m1_count{site="site1"}
+-- m1_sum{site="site1"}
+--
+-- "Inf" will be replaced by "+Inf" while publishing metrics.
+--
+-- You can find the latest version and documentation at
+-- https://github.com/knyar/nginx-lua-prometheus
+-- Released under MIT license.
+
+
+-- Default set of latency buckets, 5ms to 10s:
+local DEFAULT_BUCKETS = {0.005, 0.01, 0.02, 0.03, 0.05, 0.075, 0.1, 0.2, 0.3,
+ 0.4, 0.5, 0.75, 1, 1.5, 2, 3, 4, 5, 10}
+
+-- Metric is a "parent class" for all metrics.
+local Metric = {}
+function Metric:new(o)
+ o = o or {}
+ setmetatable(o, self)
+ self.__index = self
+ return o
+end
+
+-- Checks that the right number of labels values have been passed.
+--
+-- Args:
+-- label_values: an array of label values.
+--
+-- Returns:
+-- an error message or nil
+function Metric:check_label_values(label_values)
+ if self.label_names == nil and label_values == nil then
+ return
+ elseif self.label_names == nil and label_values ~= nil then
+ return "Expected no labels for " .. self.name .. ", got " .. #label_values
+ elseif label_values == nil and self.label_names ~= nil then
+ return "Expected " .. #self.label_names .. " labels for " ..
+ self.name .. ", got none"
+ elseif #self.label_names ~= #label_values then
+ return "Wrong number of labels for " .. self.name .. ". Expected " ..
+ #self.label_names .. ", got " .. #label_values
+ else
+ for i, k in ipairs(self.label_names) do
+ if label_values[i] == nil then
+ return "Unexpected nil value for label " .. k .. " of " .. self.name
+ end
+ end
+ end
+end
+
+local Counter = Metric:new()
+-- Increase a given counter by `value`
+--
+-- Args:
+-- value: (number) a value to add to the counter. Defaults to 1 if skipped.
+-- label_values: an array of label values. Can be nil (i.e. not defined) for
+-- metrics that have no labels.
+function Counter:inc(value, label_values)
+ local err = self:check_label_values(label_values)
+ if err ~= nil then
+ self.prometheus:log_error(err)
+ return
+ end
+ self.prometheus:inc(self.name, self.label_names, label_values, value or 1)
+end
+
+local Gauge = Metric:new()
+-- Set a given gauge to `value`
+--
+-- Args:
+-- value: (number) a value to set the gauge to. Should be defined.
+-- label_values: an array of label values. Can be nil (i.e. not defined) for
+-- metrics that have no labels.
+function Gauge:set(value, label_values)
+ if value == nil then
+ self.prometheus:log_error("No value passed for " .. self.name)
+ return
+ end
+ local err = self:check_label_values(label_values)
+ if err ~= nil then
+ self.prometheus:log_error(err)
+ return
+ end
+ self.prometheus:set(self.name, self.label_names, label_values, value)
+end
+
+local Histogram = Metric:new()
+-- Record a given value in a histogram.
+--
+-- Args:
+-- value: (number) a value to record. Should be defined.
+-- label_values: an array of label values. Can be nil (i.e. not defined) for
+-- metrics that have no labels.
+function Histogram:observe(value, label_values)
+ if value == nil then
+ self.prometheus:log_error("No value passed for " .. self.name)
+ return
+ end
+ local err = self:check_label_values(label_values)
+ if err ~= nil then
+ self.prometheus:log_error(err)
+ return
+ end
+ self.prometheus:histogram_observe(self.name, self.label_names, label_values,
value)
+end
+
+local Prometheus = {}
+Prometheus.__index = Prometheus
+Prometheus.initialized = false
+
+-- Generate full metric name that includes all labels.
+--
+-- Args:
+-- name: string
+-- label_names: (array) a list of label keys.
+-- label_values: (array) a list of label values.
+-- Returns:
+-- (string) full metric name.
+local function full_metric_name(name, label_names, label_values)
+ if not label_names then
+ return name
+ end
+ local label_parts = {}
+ for idx, key in ipairs(label_names) do
+ local label_value = (string.format("%s", label_values[idx])
+ :gsub("[^\032-\126]", "") -- strip non-printable characters
+ :gsub("\\", "\\\\")
+ :gsub('"', '\\"'))
+ table.insert(label_parts, key .. '="' .. label_value .. '"')
+ end
+ return name .. "{" .. table.concat(label_parts, ",") .. "}"
+end
+
+-- Construct bucket format for a list of buckets.
+--
+-- This receives a list of buckets and returns a sprintf template that should
+-- be used for bucket boundaries to make them come in increasing order when
+-- sorted alphabetically.
+--
+-- To re-phrase, this is where we detect how many leading and trailing zeros we
+-- need.
+--
+-- Args:
+-- buckets: a list of buckets
+--
+-- Returns:
+-- (string) a sprintf template.
+local function construct_bucket_format(buckets)
+ local max_order = 1
+ local max_precision = 1
+ for _, bucket in ipairs(buckets) do
+ assert(type(bucket) == "number", "bucket boundaries should be numeric")
+ -- floating point number with all trailing zeros removed
+ local as_string = string.format("%f", bucket):gsub("0*$", "")
+ local dot_idx = as_string:find(".", 1, true)
+ max_order = math.max(max_order, dot_idx - 1)
+ max_precision = math.max(max_precision, as_string:len() - dot_idx)
+ end
+ return "%0" .. (max_order + max_precision + 1) .. "." .. max_precision .. "f"
+end
+
+-- Extract short metric name from the full one.
+--
+-- Args:
+-- full_name: (string) full metric name that can include labels.
+--
+-- Returns:
+-- (string) short metric name with no labels. For a `*_bucket` metric of
+-- histogram the _bucket suffix will be removed.
+local function short_metric_name(full_name)
+ local labels_start, _ = full_name:find("{")
+ if not labels_start then
+ -- no labels
+ return full_name
+ end
+ local suffix_idx, _ = full_name:find("_bucket{")
+ if suffix_idx and full_name:find("le=") then
+ -- this is a histogram metric
+ return full_name:sub(1, suffix_idx - 1)
+ end
+ -- this is not a histogram metric
+ return full_name:sub(1, labels_start - 1)
+end
+
+-- Makes a shallow copy of a table
+local function copy_table(table)
+ local new = {}
+ if table ~= nil then
+ for k, v in ipairs(table) do
+ new[k] = v
+ end
+ end
+ return new
+end
+
+-- Check metric name and label names for correctness.
+--
+-- Regular expressions to validate metric and label names are
+-- documented in https://prometheus.io/docs/concepts/data_model/
+--
+-- Args:
+-- metric_name: (string) metric name.
+-- label_names: label names (array of strings).
+--
+-- Returns:
+-- Either an error string, or nil of no errors were found.
+local function check_metric_and_label_names(metric_name, label_names)
+ if not metric_name:match("^[a-zA-Z_:][a-zA-Z0-9_:]*$") then
+ return "Metric name '" .. metric_name ..
+ "' contains invalid characters"
+ end
+ for _, label_name in ipairs(label_names or {}) do
+ if label_name == "le" then
+ return "Invalid label name 'le' in " .. metric_name
+ end
+ if not label_name:match("^[a-zA-Z_][a-zA-Z0-9_]*$") then
+ return "Metric '" .. metric_name .. "' label name '" .. label_name ..
+ "' contains invalid characters"
+ end
+ end
+end
+
+-- Initialize the module.
+--
+-- This should be called once from the `init_by_lua` section in nginx
+-- configuration.
+--
+-- Args:
+-- dict_name: (string) name of the nginx shared dictionary which will be
+-- used to store all metrics
+-- prefix: (optional string) if supplied, prefix is added to all
+-- metric names on output
+--
+-- Returns:
+-- an object that should be used to register metrics.
+function Prometheus.init(dict_name, prefix)
+ local self = setmetatable({}, Prometheus)
+ self.dict = ngx.shared[dict_name or "prometheus_metrics"]
+ self.help = {}
+ if prefix then
+ self.prefix = prefix
+ else
+ self.prefix = ''
+ end
+ self.type = {}
+ self.registered = {}
+ self.buckets = {}
+ self.bucket_format = {}
+ self.initialized = true
+
+ self:counter("nginx_metric_errors_total",
+ "Number of nginx-lua-prometheus errors")
+ self.dict:set("nginx_metric_errors_total", 0)
+ return self
+end
+
+function Prometheus:log_error(...)
+ ngx.log(ngx.ERR, ...)
+ self.dict:incr("nginx_metric_errors_total", 1)
+end
+
+function Prometheus:log_error_kv(key, value, err)
+ self:log_error(
+ "Error while setting '", key, "' to '", value, "': '", err, "'")
+end
+
+-- Register a counter.
+--
+-- Args:
+-- name: (string) name of the metric. Required.
+-- description: (string) description of the metric. Will be used for the HELP
+-- comment on the metrics page. Optional.
+-- label_names: array of strings, defining a list of metrics. Optional.
+--
+-- Returns:
+-- a Counter object.
+function Prometheus:counter(name, description, label_names)
+ if not self.initialized then
+ ngx.log(ngx.ERR, "Prometheus module has not been initialized")
+ return
+ end
+
+ local err = check_metric_and_label_names(name, label_names)
+ if err ~= nil then
+ self:log_error(err)
+ return
+ end
+
+ if self.registered[name] then
+ self:log_error("Duplicate metric " .. name)
+ return
+ end
+ self.registered[name] = true
+ self.help[name] = description
+ self.type[name] = "counter"
+
+ return Counter:new{name=name, label_names=label_names, prometheus=self}
+end
+
+-- Register a gauge.
+--
+-- Args:
+-- name: (string) name of the metric. Required.
+-- description: (string) description of the metric. Will be used for the HELP
+-- comment on the metrics page. Optional.
+-- label_names: array of strings, defining a list of metrics. Optional.
+--
+-- Returns:
+-- a Gauge object.
+function Prometheus:gauge(name, description, label_names)
+ if not self.initialized then
+ ngx.log(ngx.ERR, "Prometheus module has not been initialized")
+ return
+ end
+
+ local err = check_metric_and_label_names(name, label_names)
+ if err ~= nil then
+ self:log_error(err)
+ return
+ end
+
+ if self.registered[name] then
+ self:log_error("Duplicate metric " .. name)
+ return
+ end
+ self.registered[name] = true
+ self.help[name] = description
+ self.type[name] = "gauge"
+
+ return Gauge:new{name=name, label_names=label_names, prometheus=self}
+end
+
+
+-- Register a histogram.
+--
+-- Args:
+-- name: (string) name of the metric. Required.
+-- description: (string) description of the metric. Will be used for the HELP
+-- comment on the metrics page. Optional.
+-- label_names: array of strings, defining a list of metrics. Optional.
+-- buckets: array if numbers, defining bucket boundaries. Optional.
+--
+-- Returns:
+-- a Histogram object.
+function Prometheus:histogram(name, description, label_names, buckets)
+ if not self.initialized then
+ ngx.log(ngx.ERR, "Prometheus module has not been initialized")
+ return
+ end
+
+ local err = check_metric_and_label_names(name, label_names)
+ if err ~= nil then
+ self:log_error(err)
+ return
+ end
+
+ for _, suffix in ipairs({"", "_bucket", "_count", "_sum"}) do
+ if self.registered[name .. suffix] then
+ self:log_error("Duplicate metric " .. name .. suffix)
+ return
+ end
+ self.registered[name .. suffix] = true
+ end
+ self.help[name] = description
+ self.type[name] = "histogram"
+
+ self.buckets[name] = buckets or DEFAULT_BUCKETS
+ self.bucket_format[name] = construct_bucket_format(self.buckets[name])
+
+ return Histogram:new{name=name, label_names=label_names, prometheus=self}
+end
+
+-- Set a given dictionary key.
+-- This overwrites existing values, so it should only be used when initializing
+-- metrics or when explicitely overwriting the previous value of a metric.
+function Prometheus:set_key(key, value)
+ local ok, err = self.dict:safe_set(key, value)
+ if not ok then
+ self:log_error_kv(key, value, err)
+ end
+end
+
+-- Increment a given counter by `value`.
+--
+-- Args:
+-- name: (string) short metric name without any labels.
+-- label_names: (array) a list of label keys.
+-- label_values: (array) a list of label values.
+-- value: (number) value to add. Optional, defaults to 1.
+function Prometheus:inc(name, label_names, label_values, value)
+ local key = full_metric_name(name, label_names, label_values)
+ if value == nil then value = 1 end
+ if value < 0 then
+ self:log_error_kv(key, value, "Value should not be negative")
+ return
+ end
+
+ local newval, err = self.dict:incr(key, value)
+ if newval then
+ return
+ end
+ -- Yes, this looks like a race, so I guess we might under-report some values
+ -- when multiple workers simultaneously try to create the same metric.
+ -- Hopefully this does not happen too often (shared dictionary does not get
+ -- reset during configuation reload).
+ if err == "not found" then
+ self:set_key(key, value)
+ return
+ end
+ -- Unexpected error
+ self:log_error_kv(key, value, err)
+end
+
+-- Set the current value of a gauge to `value`
+--
+-- Args:
+-- name: (string) short metric name without any labels.
+-- label_names: (array) a list of label keys.
+-- label_values: (array) a list of label values.
+-- value: (number) the new value for the gauge.
+function Prometheus:set(name, label_names, label_values, value)
+ local key = full_metric_name(name, label_names, label_values)
+ self:set_key(key, value)
+end
+
+-- Record a given value into a histogram metric.
+--
+-- Args:
+-- name: (string) short metric name without any labels.
+-- label_names: (array) a list of label keys.
+-- label_values: (array) a list of label values.
+-- value: (number) value to observe.
+function Prometheus:histogram_observe(name, label_names, label_values, value)
+ self:inc(name .. "_count", label_names, label_values, 1)
+ self:inc(name .. "_sum", label_names, label_values, value)
+
+ -- we are going to mutate arrays of label names and values, so create a copy.
+ local l_names = copy_table(label_names)
+ local l_values = copy_table(label_values)
+
+ -- Last bucket. Note, that the label value is "Inf" rather than "+Inf"
+ -- required by Prometheus. This is necessary for this bucket to be the last
+ -- one when all metrics are lexicographically sorted. "Inf" will get replaced
+ -- by "+Inf" in Prometheus:collect().
+ table.insert(l_names, "le")
+ table.insert(l_values, "Inf")
+ self:inc(name .. "_bucket", l_names, l_values, 1)
+
+ local label_count = #l_names
+ for _, bucket in ipairs(self.buckets[name]) do
+ if value <= bucket then
+ -- last label is now "le"
+ l_values[label_count] = self.bucket_format[name]:format(bucket)
+ self:inc(name .. "_bucket", l_names, l_values, 1)
+ end
+ end
+end
+
+-- Present all metrics in a text format compatible with Prometheus.
+--
+-- This function should be used to expose the metrics on a separate HTTP page.
+-- It will get the metrics from the dictionary, sort them, and expose them
+-- aling with TYPE and HELP comments.
+function Prometheus:collect()
+ ngx.header.content_type = "text/plain"
+ if not self.initialized then
+ ngx.log(ngx.ERR, "Prometheus module has not been initialized")
+ return
+ end
+
+ local keys = self.dict:get_keys(0)
+ -- Prometheus server expects buckets of a histogram to appear in increasing
+ -- numerical order of their label values.
+ table.sort(keys)
+
+ local seen_metrics = {}
+ for _, key in ipairs(keys) do
+ local value, err = self.dict:get(key)
+ if value then
+ local short_name = short_metric_name(key)
+ if not seen_metrics[short_name] then
+ if self.help[short_name] then
+ ngx.say("# HELP " .. self.prefix .. short_name .. " " ..
self.help[short_name])
+ end
+ if self.type[short_name] then
+ ngx.say("# TYPE " .. self.prefix .. short_name .. " " ..
self.type[short_name])
+ end
+ seen_metrics[short_name] = true
+ end
+ -- Replace "Inf" with "+Inf" in each metric's last bucket 'le' label.
+ ngx.say(self.prefix .. key:gsub('le="Inf"', 'le="+Inf"'), " ", value)
+ else
+ self:log_error("Error getting '", key, "': ", err)
+ end
+ end
+end
+
+return Prometheus
diff --git a/manifests/init.pp b/manifests/init.pp
index fbbc8a8..52d332c 100644
--- a/manifests/init.pp
+++ b/manifests/init.pp
@@ -70,6 +70,14 @@
tag => 'nginx', # workaround PUP-2689, can remove w/ puppetmaster
3.6.2+
}
+ if $variant == 'full' {
+ file { '/etc/nginx/prometheus.lua':
+ ensure => $ensure,
+ source => 'puppet:///modules/nginx/prometheus.lua',
+ require => Package["nginx-${variant}"],
+ }
+ }
+
# Order package -> config -> service for all
# nginx-tagged config files (including all File resources
# declared within this module), and set up the
--
To view, visit https://gerrit.wikimedia.org/r/372543
To unsubscribe, visit https://gerrit.wikimedia.org/r/settings
Gerrit-MessageType: newchange
Gerrit-Change-Id: Ief5b2f0719f3edcf53bc9646c4bfccd4b6f4db24
Gerrit-PatchSet: 1
Gerrit-Project: operations/puppet/nginx
Gerrit-Branch: master
Gerrit-Owner: Gilles <gdu...@wikimedia.org>
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