heroku - how to see all the logs

Question

I have a small app on heroku   Whenever I want to see the logs I go to the command line and do   heroku logs   That only shows me about 100 lines   Is there not a way to see complete logs for our application on heroku

User · Answer

Heroku treats logs as time-ordered streams of events. Accessing *.log files on the filesystem is not recommended in such an environment for a variety of reasons.

First, if your app has more than one dyno then each log file only represents a partial view into the events of your app. You would have to manually aggregate all the files to get the full view.

Second, the filesystem on Heroku is ephemeral meaning whenever your dyno is restarted or moved (which happens about once a day)the log files are lost. So you only get at most a day's view into that single dyno's logs.

Finally, on the Cedar stack running heroku console or even heroku run bash does not connect you to a currently running dyno. It spawns a new one specifically for the bash command. This is called a one-off process. As such, you won't find the log files for your other dynos that are running the actual http processes on the one spawned for heroku run.

Logging, and visibility in general, is a first-class citizen on Heroku and there are several tools that address these issues. First, to see a real-time stream of application events across all dynos and all layers of the application/stack use the heroku logs -t command to tail output to your terminal.

$ heroku logs -t
2010-09-16T15:13:46-07:00 app[web.1]: Processing PostController#list (for 208.39.138.12 at 2010-09-16 15:13:46) [GET]
2010-09-16T15:13:46-07:00 app[web.1]: Rendering template within layouts/application
2010-09-16T15:13:46-07:00 heroku[router]: GET myapp.heroku.com/posts queue=0 wait=0ms service=1ms bytes=975
2010-09-16T15:13:47-07:00 app[worker.1]: 2 jobs processed at 16.6761 j/s, 0 failed ...

This works great for observing the behavior of your application right now. If you want to store the logs for longer periods of time you can use one of the many logging add-ons that provide log retention, alerting and triggers.

Lastly, if you want to store the log files yourself you can setup your own syslog drain to receive the stream of events from Heroku and post-process/analyze yourself.

Summary: Don't use heroku console or heroku run bash to view static log files. Pipe into Heroku's stream of log events for your app using heroku logs or a logging add-on.

User · Answer

To see the detailed log you need to put two lines in the production rb file   config logger   Logger new STDOUT  config logger level   Logger  DEBUG   and then by running  heroku logs -t   you can see the detailed logs

User · Answer

Well  the above answers are very helpful it will help you to view from the command line  Whereas if you want to check from GUI so you have to log into your Heroku account and then select your application and finally click on view logs

User · Answer

You can access your log files using Heroku s Command Line Interface  CLI Usage     If Heroku s CLI is installed and you know your application name  like https   myapp herokuapp com    then you can run the following command   heroku logs --tail --app myapp   You can also access the logs in a real-time stream using   heroku logs --source app --tail --app myapp   If the logs tell you something like this      npm ERR  A complete log of this run can be found in        npm ERR   app  npm  logs 2017-07-11T08 29 45 291Z-debug log   Then you can also access them using the bash terminal via Heroku CLI   heroku run bash --app myapp less    npm  logs 2017-07-11T08 29 45 291Z-debug log

User · Answer

I prefer to do it this way  heroku logs --tail   tee -a herokuLogs   You can leave the script running in background and you can simply filter the logs from the text file the way you want anytime

User · Answer

Also see individual streams filters    E g tail only your application logs  heroku logs --source app -t   Or see only the router logs  heroku logs --ps router   Or chain them together   heroku logs --source app --ps worker   So good

User · Answer

You can use  heroku logs -n 1500  But this is not a recommended approach in other word doesn t show you the real picture   I would suggest you plug some logging tool    sumoLogic  paper trail n all   as an add-on   They all have a free version  with few limitations  though  enough for a small app or dev env  which  will provide good insight and tool   to analyze logs

User · Answer

Update  thanks to dawmail333    heroku logs -n 1500   or  to tail the logs live   heroku logs -t    Heroku log documentation  If you need more than a few thousand lines you can Use heroku s Syslog Drains  Alternatively  old method      heroku run rails c File open  log production log    r   each line    line  puts line

User · Answer

I was running into a situation where in my apps  dashboard  when I went to  More  gt  View logs  I wouldn t get an output  just hung    So I did a google and found this   Heroku CLI plugin to list and create builds for Heroku apps   I installed it and ran  heroku builds -a example-app    Lists 10 most recently created builds for example-app  that s where you get the id for the next step    Then enter  heroku builds output your-app-id-number -a example-app   And that s it  you should get back what you normally see in the dashboard GUI or locally  Hope this helps someone like it did me

User · Answer

for WAR files   I did not use github  instead I uploaded directly  a WAR file   which I found to be much easier and faster     So the following helped me   heroku logs --app appname   Hope it will help someone

User · Answer

heroku logs -t shows us the live logs

User · Answer

Follow on Heroku logging  To view your logs we have    logs command retrives 100 log lines by default       heroku logs    show maximum 1500 lines  --num  or -n  option       heroku logs -n 200    Show logs in real time      heroku logs --tail    If you have many apps on heroku      heroku logs --app your app name

User · Answer

You need to have some logs draining implemented and should be draining your logs there  to see all of the logs  manage historical logs as well      First option - Splunk can be used  you can drain all your logs like    heroku drains add  syslog tls   splunk-server com 514  -a app name  And then login into your splunk server and search for any number of logs  I am using Splunk and this is working perfectly fine for me    Second option - You can purchase add on to your App  like given below   I haven t used these options  however these are the available ones     Timber io Sumo Logic LogEnteries Log DNA Papertrail       You can also have a look at below options  If you want to have your   logs in JSON format  as it will help if your are pushing your logs to   external system like Splunk ELK  it would become easy  performance   wise also  to search in JSON    https   github com goodeggs heroku-log-normalizer  It is not having Readme md  but some explanation is given at https   github com goodeggs bites issues 20  Lastly  And you can always use below command as mentioned by other users already   The following command will tail the generating logs on heroku  heroku logs -t -a  lt app name gt    The following comand will show the 1000 number of lines of logs from heroku  heroku logs -n 1000 -a  lt app name gt       Note only 1500 latest lines of logs are available and rest of them gets deleted from heroku dyno

User · Answer

You need to use -t or --tail option and you need to define your heroku app name   heroku logs -t --app app name

User · Answer

My solution is to get complete log the first time the application start  like   heroku logs -n 1500  gt  log   then add fgrep -vf to keep it up to date  like   heroku logs -n 1500  gt  newlog   fgrep -vf log newlog  gt  gt  log   for continuous logging  just iterate it using watch for every x minutes  or seconds

User · Answer

Logging has greatly improved in heroku     heroku logs -n 500   Better     heroku logs --tail   references  http   devcenter heroku com articles logging  UPDATED  These are no longer add-ons  but part of the default functionality

User · Answer

heroku logs -t  shows us the live logs  heroku logs -n 1500 for  specific number of logs  But still I would recommend to use paper trail add-on which have certain benefits and has free basic plan

User · Answer

I suggest using an addon  I use Logentries  To use it  run in your command line   heroku addons create logentries le tryit   that command creates the addon for a free account but clearly you can upgrade if you want   Logentries allows you to save up to 5GB of log volume per month  That info is searchable by their command search within the last 7 days and it has real-time alerts   So to answer your question  by using this addon you ensure that your logs aren t lost anymore when you reach the 1500 lines that Heroku saves by default   Hope this helps  Have a great day

User · Answer

Might be worth it to add something like the free Papertrail plan to your app  Zero configuration  and you get 7 days worth of logging data up to 10MB day  and can search back through 2 days of logs

User · Answer

For cedar stack see   https   devcenter heroku com articles oneoff-admin-ps  you need to run   heroku run bash

[heroku] heroku - how to see all the logs

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