Failed to create a pidfile: no such file or directory

[aereal]

Tried to run mackerel-agent that installed by latest Homebrew tap on my refreshed OS X and caught these errors:

$ cd /usr/local/var/mackerel-agent; mackerel-agent -conf /usr/local/etc/mackerel-agent.conf
2015/10/05 11:10:34 main.go:84: INFO <main> Starting mackerel-agent version:0.23.0, rev:5dd63a4, apibase:https://mackerel.io
2015/10/05 11:10:34 main.go:272: CRITICAL <main> Failed to create a pidfile: open /Users/aereal/Library/mackerel-agent/pid: no such file or directory

I confirmed that the directory (~/Library/mackerel-agent) does not exist.

(Missing preparation? (such as mkdir -p conf.Root))

mackerel-agent.conf:

# pidfile = "/var/run/mackerel-agent.pid"
# root = "/var/lib/mackerel-agent"
verbose = true
apikey = "<censored>"

# Configuration for connection
# [connection]
# post_metrics_dequeue_delay_seconds = 30 # delay for dequeuing from buffer queue
# post_metrics_retry_delay_seconds = 60   # delay for retring a request that causes errors
# post_metrics_retry_max = 10             # max numbers of retries for a request that causes errors
# post_metrics_buffer_size = 30           # max numbers of requests stored in buffer queue.

# Configuration for Custm Metrics Plugins
# see also: http://help-ja.mackerel.io/entry/advanced/custom-metrics

# followings are mackerel-agent-plugins https://github.com/mackerelio/mackerel-agent-plugins

# Plugin for Apache2 mod_status
#   By default, the plugin accesses to http://127.0.0.1/server-status?auto
# [plugin.metrics.apache2]
# command = "/usr/local/bin/mackerel-plugin-apache2"

# Plugin for EC2 CPU Credit
# [plugin.metrics.aws-ec2_cpucredit]
# command = "/usr/local/bin/mackerel-plugin-aws-ec2-cpucredit"

# Plugin for AWS ELB
# [plugin.metrics.aws-elb]
# command = "/usr/local/bin/mackerel-plugin-aws-elb"

# Plugin for Amazon RDS
# [plugin.metrics.aws-rds]
# command = "/usr/local/bin/mackerel-plugin-aws-rds -identifier=<required>"

# Plugin for Elasticsearch
#   By default, the plugin accesses Elasticsearch on localhost.
# [plugin.metrics.elasticsearch]
# command = "/usr/local/bin/mackerel-plugin-elasticsearch"

# Plugin for HAProxy
#   By default, the plugin accesses Elasticsearch on localhost.
# [plugin.metrics.haproxy]
# command = "/usr/local/bin/mackerel-plugin-haproxy"

# Plugin for JVM
#   Required javaname
# [plugin.metrics.jvm]
# command = "/usr/local/bin/mackerel-plugin-jvm -javaname=<required>"

# Plugin for Linux
# [plugin.metrics.linux]
# command = "/usr/local/bin/mackerel-plugin-linux"

# Plugin for Memcached
# [plugin.metrics.memcached]
# command = "/usr/local/bin/mackerel-plugin-memcached"

# Plugin for MongoDB
# [plugin.metrics.mongodb]
# command = "/usr/local/bin/mackerel-plugin-mongodb"

# Plugin for MySQL
#   Appropriate previlege settings required.
#   By default, the plugin accesses MySQL on localhost by 'root' with no password.
# [plugin.metrics.mysql]
# command = "/usr/local/bin/mackerel-plugin-mysql"

# Plugin for Nginx
#   By default, the plugin accesses to http://localhost:8080/nginx_status
# [plugin.metrics.nginx]
# command = "/usr/local/bin/mackerel-plugin-nginx"

# Plugin for PHP APC
# [plugin.metrics.php-apc]
# command = "/usr/local/bin/mackerel-plugin-php-apc"

# Plugin for Plack
#   By default, the plugin accesses to http://localhost:5000/server-status?json
# [plugin.metrics.plack]
# command = "/usr/local/bin/mackerel-plugin-plack"

# Plugin for PostgreSQL
#   Appropriate previlege settings required.
#   By default, the plugin accesses PostgreSQL on localhost.
# [plugin.metrics.postgres]
# command = "/usr/local/bin/mackerel-plugin-postgres"

# Plugin for Redis
#   By default, the plugin accesses Redis on localhost.
#   Currently AUTH password has not been supported yet.
# [plugin.metrics.redis]
# command = "/usr/local/bin/mackerel-plugin-redis"

# Plugin for SNMP
# [plugin.metrics.pps]
# command = "/usr/local/bin/mackerel-plugin-snmp -name='pps' -community='private' '.1.3.6.1.2.1.31.1.1.1.7.2:eth01in:1:0' '.1.3.6.1.2.1.31.1.1.1.11.2:eth01out:1:0'"

# Plugin for Squid
# [plugin.metrics.squid]
# command = "/usr/local/bin/mackerel-plugin-squid"

# Plugin for Varnish
# [plugin.metrics.varnish]
# command = "/usr/local/bin/mackerel-plugin-varnish"

# Plugin for munin (wrapper)
# [plugin.metrics.nfsd]
# command = "/usr/local/bin/mackerel-plugin-munin -plugin=/usr/share/munin/plugins/nfsd"
# [plugin.metrics.bind9]
# command = "/usr/local/bin/mackerel-plugin-munin -plugin=/etc/munin/plugins/bind9 -plugin-conf-d=/etc/munin/plugin-conf.d"
# [plugin.metrics.postfix]
# command = "MUNIN_LIBDIR=/usr/share/munin /usr/local/bin/mackerel-plugin-munin -plugin=/usr/share/munin/plugins/postfix_mailqueue -name=postfix.mailqueue"

# followings are other samples
# [plugin.metrics.vmstat]
# command = "ruby /etc/sensu/plugins/system/vmstat-metrics.rb"
# [plugin.metrics.curl]
# command = "ruby /etc/sensu/plugins/http/metrics-curl.rb"

Versino info.:

$ mackerel-agent --version
mackerel-agent version 0.23.0 (rev 5dd63a4) [darwin amd64 go1.4]
$ uname -a
Darwin Hortensia.local 15.0.0 Darwin Kernel Version 15.0.0: Wed Aug 26 16:57:32 PDT 2015; root:xnu-3247.1.106~1/RELEASE_X86_64 x86_64 i386 MacBookPro10,2 Darwin
$ go version
go version go1.5.1 darwin/amd64
$ brew --version
0.9.5 (git revision 648a; last commit 2015-10-05)