So I've recently posted a few links on Twitter, and I see followers clicking them. But also I see random hits.
Within two minutes I had 15 visitors the first few of which were:IP User-Agent Request 184.108.40.206Twitterbot/1.0;GET /robots.txt 220.127.116.11Twitterbot/1.0;GET /robots.txt 18.104.22.168python-requests/1.2.3 CPython/2.7.2+ Linux/3.0.0-16-virtualHEAD / 22.214.171.124Mozilla/5.0 ();GET / 126.96.36.199Google-HTTP-Java-Client/1.17.0-rc (gzip)HEAD / 188.8.131.52Google-HTTP-Java-Client/1.17.0-rc (gzip)HEAD / 184.108.40.206Twitterbot/1.0;GET /robots.txt 220.127.116.11Mozilla/5.0 (compatible; TweetmemeBot/3.0; +http://tweetmeme.com/)GET / 18.104.22.168MetaURI API/2.0 +metauri.comGET / 22.214.171.124Mozilla/5.0 (compatible; Yahoo! Slurp; http://help.yahoo.com/help/us/ysearch/slurp);GET /robots.txt
So what jumps out? The twitterbot makes several requests for /robots.txt, but never actually fetches the page itself which is interesting because there is indeed a prohibition in the supplied /robots.txt file.
A surprise was that both Google and Yahoo seem to follow Twitter links in almost real-time. Though the Yahoo site parsed and honoured /robots.txt the Google spider seemed to only make HEAD requests - and never actually look for the content or the robots file.
In addition to this a bunch of hosts from the Amazon EC2 space made requests, which was perhaps not a surprise. Some automated processing, and classification, no doubt.
Anyway beer. It's been a rough weekend.
Last year I removed all my music from Google Play Music and created my own subSonic server. I really like subSonic but don't use it a huge amount, mostly for syncing some music to my phone prior to going on holiday or business. Therefore, I've made a single one time donation to the project rather than the ongoing monthly usage fee.Installing subSonic on Debian
This is how I install subSonic on Debian Wheezy.Install Tomcat. sudo apt-get install tomcat7 Install subSonic. apt-get install ffmpeg sudo mkdir /var/subsonic sudo chown tomcat7: /var/subsonic sudo wget -c https://github.com/KHresearch/subsonic/releases/download/v4.9-kang/subsonic.war sudo cp subsonic.war /var/lib/tomcat7/webapps
Restart Tomcat.sudo service tomcat7 restart
Login to subSonic by visiting http://server.example.org:8080/subsonic and login with the credentials admin and admin. Make sure you change the password straight away.
Right, that is it. You can stop here and start filling subSonic with your music.subSonic clients
So recently I got into trouble running Redis on a host, because the data no-longer fits into RAM.
As an interim measure I fixed this by bumping the RAM allocated to the guest, but a real solution was needed. I figure there are three real alternatives:
Looking around I found a couple of Redis-alternatives, but I was curious to see how hard it would be to hack something useful myself, as a creative solution.
This evening I spotted Protocol::Redis, which is a perl module for decoding/encoding data to/from a Redis server.
It's a limited implementation which stores data in an SQLite database, and currently has support for:
It isn't hugely fast, but it is fast enough, and it should be possible to use alternative backends in the future.
I suspect I'll not add sets/hashes, but it could be done if somebody was keen.
As my previous post suggested I'd been running a service for a few years, using Redis as a key-value store.
Redis is lovely. If your dataset will fit in RAM. Otherwise it dies hard.
Inspired by Memcached, which is a simple key=value store, redis allows for more operations: using sets, using hashes, etc, etc.
As it transpires I mostly set keys to values, so it crossed my mind last night an alternative to rewriting the service to use a non-RAM-constrained service might be to juggle redis out and replace it with something else.
If it were possible to have a redis-compatible API which secretly stored the data in leveldb, sqlite, or even Berkley DB, then that would solve my problem of RAM-constraints, and also be useful.
Anyway the short version is that this might be a way forward, the real solution might be to use sqlite or postgres, but that would take a few days work. For the moment the service has been moved to a donated guest and has 2Gb of RAM instead of the paltry 512Mb it was running on previously.
Happily the server is installed/maintained by my slaughter tool so reinstalling took about ten minutes - the only hard part was migrating the Redis-contents, and that's trivial thanks to the integrated "slave of" support. (I should write that up regardless though.)
I’ve finally worked out how to create self-signed SSL certificates for multiple domain names with openssl.
These notes relate to Debian GNU/Linux, but the principles will apply to other operating systems.
The first step to make the process easier and repeatable in the future is to copy the default configuration file from /etc/ssl/openssl.cnf to a working directory where you can adapt it
Let’s assume that you’ve copied /etc/ssl/openssl.cnf to ~/project-openssl.cnf. Edit the new file and set the various default values to the ones that you need — that’s better than having to respond to openssl’s prompts every time you run it.
For real non-self-signed certificates, you would generate a certificate signing request (.csr) file, ready for a certificate authority to sign it for you. In that case, you need to follow the instructions at http://wiki.cacert.org/FAQ/subjectAltName.
But for a self-signed certificate, the subjectAltName has to go in a different place. Make sure you’ve got this line present and un-commented in the [req] section of the config file:[req] ... x509_extensions = v3_ca
and then this goes at the end of the [v3_ca] section:[v3_ca] ... subjectAltName = @alt_names [alt_names] DNS.1 = example.com DNS.2 = www.example.com DNS.3 = example.co.uk DNS.4 = www.example.co.uk
There is (apparently) a limit to the number (or total length) of the alternate names, but I didn’t reach it with 11 domain names.
It’s also possible to add IP addresses to the alt_names section like this:IP.1 = 192.168.1.1 IP.2 = 192.168.69.14
Then to create the key and self-signed certificate, run commands similar to these:openssl req -x509 -nodes -days 3650 -newkey rsa:2048 -keyout project.key -out project.crt -config ~/project-openssl.cnf cp project.crt /etc/ssl/localcerts/ mv project.key /etc/ssl/private/
Note that I move (rather than copy) the key to the private directory to avoid leaving a copy of it lying around unprotected.
You can check that the certificate contains all the domains that you added by running this:openssl x509 -in project.crt -text -noout | less Alternative approach
I haven’t tried this, but according to http://apetec.com/support/GenerateSAN-CSR.htm it’s also possible to create a CSR and then self-sign it like this:openssl x509 -req -days 3650 -in project.csr -signkey project.key -out project.crt v3_req -extfile project-openssl.cnf References:
Once upon a time I setup a centralized service for spam-testing blog/forum-comments in real time, that service is BlogSpam.net.
This was created because the Debian Administration site was getting hammered with bogus comments, as was my personal blog.
Today the unfortunate thing happened, the virtual machine this service was running on ran out of RAM and died - The redis-store that holds all the state has now exceeded the paltry 512Mb allocated to the guest, so OOM killed it.
So I'm at an impasse - I either recode it to use MySQL instead of Redis, or something similar to allow the backing store to exceed the RAM-size, or I shut the thing down.
There seems to be virtually no liklihood somebody would sponsor a host to run the service, because people just don't pay for this kind of service.
I've temporarily given the guest 1Gb of RAM, but that comes at a cost. I've had to shut down my "builder" host - which is used to build Debian packages via pbuilder.
Offering an API, for free, which has become increasingly popular and yet equally gets almost zero feedback or "thanks" is a bit of a double-edged sword. Because it has so many users it provides a better service - but equally costs more to run in terms of time, effort, and attention.
(And I just realized over the weekend that my Flattr account is full of money (~50 euro) that I can't withdraw - since I deleted my paypal account last year. Ooops.)
Happy news? I'm avoiding the issue of free service indefinitely with the git-based DNS product which was covering costs and now is .. doing better. (20% off your first months bill with coupon "20PERCENT".)